1. Field of Invention
This invention relates to lighting assemblies and more particularly to apparatus and processes for producing distinguishable light in the presence of ambient light.
2. Description of Related Art
High brightness light emitting diodes (LEDs) are being used more frequently in various applications including automotive signal lights or taillights, for example. LEDs directly emit colored light without any additional colored filters, which allows automobile designers to craft signal lamp designs with clear outer lenses and reflectors which tend to be more attractive aesthetically than conventional designs. Unfortunately, the use of clear outer lenses and reflectors in signal lamp designs can result in poor daytime visibility. This is because light from the sun can enter the lamp housing and be reflected with little or no losses. This light mixes with light from the LED signal source and to an external observer, this mixed light appears less color saturated or “washed out” and thus, less visible. Other drivers may have difficulty seeing signal lights suffering from this problem and this can create a traffic hazard.
Typical methods for improving daytime visibility of signal lights involves the use of colored external lenses, the use of an optical structure on an outer lens or a matte or structured outer lens or reflector. Each of these methods has limited effectiveness and significantly changes the appearance of the signal lamp in a way that may be objectionable to automobile designers.